What Affects Solar Panel Cost: 8 Price Drivers with Dollar Ranges and 4 Worked 6.6kW Quotes (October 2026)

Four worked quotes for the same 6.6 kW system

Every quote below is the same hardware: 6.6 kW of panels and a 5 kW inverter at the national standard offer of $6,774 after STCs, or $8,084 at the premium offer. Only the house changes. Scenario A is the house the index assumes. Scenario B adds edge protection or scaffold at $1,000 to $3,500 and tile-roof labour at $200 to $600, so the same system costs $7,974 to $10,874, which is 18 to 61 per cent more. Scenario C adds a three-phase inverter at $375 to $1,500. Scenario D adds optimisers or microinverters at $1,500 to $2,000.

Each add-on should appear on your quote as its own line. A quote that folds them into one number cannot be compared with the next quote. The quote breakdown page shows the full line list; the quote check compares your total with the band for your city.

What each scenario costs per kWh over 25 years

Divide each total by 25 years of output and the add-ons shrink. A 6.6 kW system in Sydney makes about 221,388 kWh over 25 years at 1,424 kWh per kW a year with 0.5 per cent annual degradation. The base system costs 3.1 cents per kWh at the standard offer and 3.7 cents at the premium offer. The two-storey tile roof in scenario B costs 3.6 to 4.9 cents, which is 0.5 to 1.8 cents more per kWh than scenario A. The grid rate in New South Wales is 34 cents.

Scenario D is the one case where the add-on also changes the output. Optimisers or microinverters recover some of the generation a shaded string loses; we have no sourced figure for how much on an Australian roof, so the table prices the hardware and holds output constant. Ask the installer for a shade analysis with and without the device.

Roof material: tile against tin

Tile adds $200 to $600 in labour to a 6.6 kW job. Tiles are lifted and replaced or ground to fit hooks, and the crew moves more slowly on them. The mounting hardware also costs more: a 2 kW tile kit lists at $116 against $56 for the tin kit on the same trade list, ex GST, so the hardware premium across a 15-panel system is about $244 before GST. Slate, terracotta in poor condition and asbestos-cement roofs sit outside both figures and need a site visit before any price is given.

Storeys: edge protection and scaffold

Two storeys add $1,000 to $3,500 per job for roof edge protection or scaffold, supplied, installed and dismantled. Work health and safety rules treat work with a potential fall of two metres or more as high-risk construction work that needs a safe work method statement, and a two-storey roof is above that line. This is the largest single add-on in the table, larger than the three-phase or shading items, and it is the one most often missing from a satellite quote. If a two-storey quote shows no access line, ask how the crew will be protected and who pays if the answer is a scaffold on the day.

Phase: single or three

A three-phase inverter costs $375 to $1,500 more than the single-phase unit for the same job. The low end is the trade price gap between a three-phase and a single-phase 5 kW inverter of the same model family, ex GST; the high end is an installed estimate. Three phase is not a cost to avoid: it lifts the inverter size and export limit most networks allow, which is what makes a 10 kW system worth buying. Converting a single-phase supply to three phase is separate work billed by an electrician and your network, and we have no sourced figure for it. The network limits are on each city page.

Shading: optimisers and microinverters

A shaded roof is usually quoted with microinverters or DC optimisers, which cost $1,500 to $2,000 more than a string inverter at system level. That range is the difference between two installed estimates, not a trade list, because no Australian price list publishes a per-unit price for a residential microinverter or an optimiser; the distributor lists are login only. What would settle it is a public Australian trade price for one microinverter unit and one optimiser unit, which we will add to the data the month one appears. Until then, ask for the per-panel device price as a line on the quote and multiply it by the panel count yourself.

Switchboard upgrade

A switchboard upgrade costs $500 to $2,500 and is never in the base price. The low end covers a modification to make a modern board solar ready; the high end is a full replacement of a ceramic-fuse or asbestos-backed board. A satellite quote cannot see your switchboard, so the quote should either price it from a photo you send or state in writing that it is excluded and what a replacement would cost.

Distance, travel and cable runs

Two drivers carry no dollar figure on this page because no dated Australian source publishes one: a travel surcharge outside the metro area, and a long cable run between the array and the switchboard. The index prices used across this site exclude travel. What would settle each: a published per-kilometre or per-job travel charge from an installer's price schedule, and a published per-metre installed cable rate. If your quote carries either item, it should state the kilometres or metres and the rate, so the line can be checked.

Panel tier: what the panels themselves cost

Panel supply prices on the trade list run 0.37 to 0.45 dollars per watt for budget n-type panels, 0.50 to 0.51 for the mid range and 0.60 to 0.80 for premium heterojunction or back-contact panels, ex GST. Multiplied by 6,600 W that is $2,442 to $2,970 of panels in a budget system and $3,960 to $5,280 in a premium one: a gap of $990 to $2,838 before GST. The index shows the same thing from the other side: the premium offer is $1,310 above the standard offer at 6.6 kW, 19 per cent. The premium buys longer product warranties and lower degradation on the datasheet, which the cost pillar tabulates by model.

Inverter type

The inverter is the second largest hardware line and the one that moves most between quotes. A budget-class 5 kW string inverter lists at $1,090 ex GST on a public trade page; a Fronius-class 5 kW unit lists at $2,444, which is $1,354 more for the same rating. A hybrid inverter that can take a battery later runs $3,449 to $5,399. Those are supply prices; a quote marks them up and adds the labour, which does not change with the brand.

Where the table says no list price was found, the quote is the only source: ask for the per-unit price and the model number, and check the model on the approved inverter list.

Location: STC zone and the city index

Where the house is changes the price twice. First the STC discount: a 6.6 kW system earns 45 certificates in Zone 3 (Sydney, Brisbane, Perth, Adelaide) and 39 in Zone 4 (Melbourne, Hobart, Canberra). At $39 per certificate that is $1,755 against $1,521, a gap of $234. Your quote's STC line should sit within 10 per cent of those figures for your zone; a lower figure means the installer is pricing certificates below spot trades and recovering the difference elsewhere. Second the market: the same standard 6.6 kW offer is $5,294 in Perth and $10,250 in Darwin, $4,956 or 94 per cent more, with Sydney at $6,170 and Melbourne at $6,218. From 1 January 2027 the deeming period drops from 5 to 4 years: the Zone 3 discount falls to 36 certificates and $1,404, which adds $351 to the price of every 6.6 kW system installed after that date unless hardware prices fall by as much.

Smaller line items

Three items turn up often enough to price.

System size is the other driver people ask about, and it works the opposite way: the fixed costs spread over more panels, so bigger systems cost less per watt. The cost per watt page has that arithmetic.

Solar cost driver questions